The way that the electric charge control type ink-jet printing device works is to eject pressured ink from a nozzle, to give an electric charge from a charged electrode to these ink particles by applying the charged voltage which is to become a letter signal, to deflect the charged particles vertically in inclination electric fields, and to form the letter to a printing object moving approximately perpendicularly to the direction that the ink particles deflect, and the electric charge control type ink-jet printing device is put to practical use by uses such as the printing in the expiration date to foods. It is preferable to detect leak of ink or solvent of such kind of the ink-jet printing device, because it is difficult to completely prevent leak from the course (tube and joint) and the containers that occur for some causes.
A method mentioned in the non-patent document 1 is generally and conventionally used to detect leak; in order to detect leak, the device comprising a exclusive sensor for the leak detection in the floor region of the device, and detecting ink or solvent which collected into floor region by the sensor.